Concentrations of 90Sr, 137Cs, 238Pu, 239+240Pu, and 241Am in deer mice tissues collected from a radioactive waste disposal area in southeastern Idaho were significantly (p less than 0.05) higher than those from a control area. The highest concentrations of Pu and Am occurred in pelts of deer mice inhabiting an area which had elevated surface and subsurface soil concentrations of these nuclides as compared to other Subsurface Disposal Area locations. Therefore, transuranic contamination in tissues likely originated from both soil depths. However, 137Cs and 90Sr in tissues likely originated from subsurface areas, since surface soils were below background concentrations for these nuclides. Based on a minimum of 6160 deer mice inhabiting the 36-ha waste disposal area over a 1-yr period, a total minimum inventory of 22.8 mu Ci radioactivity was contained in deer mice tissues. Of this estimate, 22.7 mu Ci activity was due to the radionuclides 90Sr and 137Cs. An estimated total of 8.4 mu Ci was transported from the disposal area in mice dispersing from the area. A calculated annual radionuclide inventory of 28.8 mu Ci in deer mice feces was deposited in and around the radioactive waste disposal area. Deer mice inhabiting the SDA are a mode of radionuclide uptake and transport; however, the environmental consequences of this transport mechanism are likely minimal. The results for deer mice, which make up 69% of the small mammal biomass, are discussed in relation to other small mammals within the disposal area. Other modes of transport associated with the deer mice, such as radionuclides in excavated soils associated with burrowing activities and predation, are also discussed.
Over 3 100 ducks, geese, swans and American coots (Fulica arnericana) were censused at the Test Reactor Area (TRA) radioactive leaching ponds on the Idaho National Engineering Laboratory (INEL) Site from January 1974 through March 1978. Twenty-six ducks and two American coots were collected from the TRA ponds from January 1974 through December 1977, and tissues were analyzed for y-emitting radionuclides. Duck tissues contained up to 29 radionuclides. Total average and maximum radionuclide concentrations were highest in gut followed by feathers. liver, muscle and skin. Chromium-51 had the highest relative radionuclide concentration identified (130,000 pCi/g-gut and 37,500 pCi/g-feathers). Cesium-137 was the predominant radionuclide in muscle with a maximum concentration of 4070 pCi/g. Edible duck tissues (muscle, liver and skin) had lower radionuclide concentrations than non-edible tissues (gut and feathers). The total amount of radioactivity being exported from the TRA environs during the 4-yr study period was estimated to be 5 x Ci. Cesium-137, 134Cs, and I3'I contributed 98% of the calculated potential radiation dose equivalent to man. The potential whole-body and thyroid dose commitment to man from consuming one waterfowl that was contaminated with the average radionuclide concentrations observed would be 12 and 7 mrem, respectively.
Thyroids were collected from rabbits on and near the Idaho National Engineering Laboratory (INEL) Site in southeastern Idaho and analyzed for 129I and stable iodine, 127I. The 129I/127I atom ratios in rabbits collected on the INEL site were larger than ratios in rabbits from a control area. Maximum 129I/127I atom ratios (9.1 x 10(-4)) occurred near the Idaho Chemical Processing Plant (ICPP). Based on rabbit thyroid concentrations, the 129I appeared to be deposited primarily in the direction of the predominant winds from the ICPP, northeast and southwest. Dose rates from the 129I to thyroids of INEL rabbits varied from 0.1 to 260 muGy/y (0.01 to 26 mrad/y). Iodine-129 atmospheric releases from the ICPP appeared to have increased the 129I/127I atom ratios on and near the INEL site.
The biological elimination of nine gamma-emitting radioisotopes was studied in mallards (Anas platyrhynchos) which were released onto liquid radioactive waste pounds in southeastern Idaho. After 68, 75 or 145 days, the ducks were removed from the contaminated environment and placed in metabolic cages. Whole-body and feces-urine counts were made for 51 days and then the ducks were sacrificed and dissected for tissue analyses. The biological elimination of radioisotopes were fit to two compartment models using non-linear least squares estimation. Fecal-urine data substantiated two-compartment elimination of all radionuclides. Biological half-lives in mallards were 10 days (131I), 22 days (140Ba), 86 days (51Cr), 32 days (58Co), 26 days (75Se), 67 days (65Zn), 10 days (134Cs), 67 days (60Co) and 11 days (137Cs). Body burdens in ducks were at 90% of equilibrium with the radioactive waste pond water at the time of removal from the waste ponds. Tissue distribution of radionuclides on the day of removal from the ponds showed gut to have the highest concentrations followed by feather, liver and muscle. After 51 days in metabolic cages, feather had the greatest radionuclide concentrations followed by liver, muscle and gut. Liver contained the greatest variety of radionuclides and muscle the smallest. Biological elimination rates for the major dose-contributing nuclides (134Cs and 137Cs) to humans consuming contaminated waterfowl tissue indicate that the dose to man could be reduced substantially due to the rapid elimination of these radionuclides by mallards. Contaminated waterfowl would receive most of the internal dose in the first month after leaving the contaminated environment indicating that long-term doses would be inconsequential.
Deposition velocities and retention times were obtained for submicron aerosols of 141Ce and 13l4Cs deposited on two cool desert plant species, big sagebrush (Artemisia tridentata) and bottlebrush grass (Sitanion hystrix). Mean deposition velocities for sagebrush were 0.18 cm/s (141Ce) and 0.13 cm/s (134Cs). Mean deposition velocities for grass were 0.022 (141Ce) and 0.023 cm/s (134Cs). Species differences were significant (p less than 0.05), however, nuclide differences were not significant. The loss of activity on the vegetation consisted of two components. A rapid initial loss was found with effective half-times of approx. 1 d (1-8 d for 141Ce and 0.6 d for 134Cs) on sagebrush and approx. 2 d (2.8 d for 141Ce and 2.3 d for 134Cs) on grass. This was followed by a slower, long-term loss with effective half-times ranging from 11 d for 141Ce and 15 d for 134Cs on sagebrush to 9 d for 141 Ce and 11 d for 134Cs on grass.
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